The present invention relates to a rubber composition, more particularly, to a rubber composition capable of giving a vulcanizate having excellent heat resistance, recoverability from compression, electric insulation, weatherability and surface lubricity.
The rubber compositions of this invention are compounded with a mixture of an ethylene-propylene copolymer and an organopolysiloxane as the base rubber and are suitable for use as automobile parts such as plug caps, plug boots, insulation of ignition cords, weather strips and the like as well as for the production of foamed celular or spongy rubber articles suitable as automobile parts such as sponge gaskets, weather strips, sponge hoses of protectors and the like and powder puffs for makeup when vulcanized with blowing using a blowing agent.
Rubber compositions compounded with an ethylene-propylene copolymer and an organopolysiloxane in general are capable of giving a rubber vulcanizate having excellent heat resistance, low permanent compression set and high electric insulation and they are widely used to produce a variety of automobile parts including injection-molded articles such as plug caps, plug boots and the like and extrusion-molded articles such as insulation of ignition cords and the like. A defect in the rubber vulcanizates of these rubber compositions is poor surface slipperiness so that, for example, extrusion-molded articles such as weather strips and the like have poor surface lubricity which does not to ensure smooth sliding on glass surfaces.